This invention relates to amphibious tracklaying vehicles.
Previous amphibian tracklaying vehicles have included a variety of military landing craft and wetland machinery. Military landing craft have tracks at opposite sides of an open barge-like hull. Different from this invention, the open barge-like hull is not an enclosed buoyant pontoon and the tracks are relatively narrow in order to allow loading and unloading of the hull between the tracks. Also known is a catamaran amphibious tracklaying vehicle having pontoon hulls joined in juxtaposed relationship. Propulsive traction was provided by a track on each pontoon. Conventional snow tractors also are different. They do not have a pontoon hull or buoyant frame, although they have tracks that are relatively wide but not full-width from side-to-center as in this invention. Tracklaying tractors in general are further yet different. They have neither a pontoon hull nor full-width side-to-center tracks as taught by this invention.
Wetland tractors have unique problems resulting from a buoyance necessity in combination with severe puncture conditions aggravated by high weight of buoyant hulls that are large enough and sturdy enough to support heavy-duty equipment. This is in addition to high traction requirements for operating in mud, slime and other slippery terrain conditions.
A wide variety of efforts have been made to solve numerous problems involved. U.S. Pat. No. 4,846,092 granted to Paul Wilson on Jul. 11, 1989 describes an amphibious tracklaying vehicle with at least one pontoon and buoyant cleats. The particular type of buoyant cleats it taught had a trapezoidal cross section in the form of a truncated triangle. While providing high structural integrity, the Wilson cleat tended to embed into soft surfaces and did not provide adequate buoyancy. Although the claims in the Wilson patent described at least one pontoon hull enveloped by an endless drive track, it did not teach a single pontoon hull enveloped by two endless drive tracks juxtaposed from side to center of a single pontoon hull. Nor did it teach either buoyant or non-buoyant step cleats on such a single-pontoon amphibious vehicle. Further, it did not teach a scraper cleat for removing gummy mud and related debris that obstruct movement of tracks. Also, it did not provide suspension for a deck positioned above a pontoon hull. Other known wetland and tracklaying vehicles are further yet different from the amphibious all-terrain tracklaying vehicle taught by this invention.